Chemical Kinetics

Kinetic Molecular Theory

1. a gas is composed of molecules that possess mass but have negligible volume.

2. gas molecules are in constant motion in random directions, and they frequently collide with one another.

3. These collisions are elastic (bounce off each other)

4. gas molecules do not attract or repel each other

5. Kinetic energy (KE) is directly proportional to Kelvin Temperature.

Collision Theory

In a chemical reaction, bonds are broken, and new bonds are formed. Molecules can only react if they collide with each other.

In order for a chemical reaction to occur, there needs to be…

1. Sufficient energy

2. proper orientation of molecules

Activation Energy

The minimum amount of energy that colliding molecules need in order for a successful collision to occur…leading to a chemical reaction.

LOOK AT GRAPHS

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Rate of Reaction

change in concentration of a reactant or product per unit of time.

Things that can affect rate of reaction

1. temperature

2. pressure

3. concentration

4. surface area of the particles (bigger particles = less surface area = slower rate of reaction and vice versa for smaller particles!)

5. presence of a catalyst (lowers activation energy bc it makes it easier to react bc the process including a catalyst requires less energy to get started)

6. LOOK AT CATALYST GRAPH

In order to raise the rate of reaction…

there needs to be more frequent collisions that are successful.

What is a rate law? what is the proportionality constant called?

Equation that shows relationship between concentration of reactants and rate of reaction. Rate constant is what its called (also k in the equation).

what is meant by the order of a reaction/order overall?

all of the exponents added together.

standard unit for chemical reaction rates

mol/dm3